In firewall and proxy products, a policy is composed of a set of conditions which, when evaluated against network traffic, cause the proxy device to apply a policy decision, such as allowing or denying the traffic. Generally, the conditions are based on an attribute of the network traffic such as an application associated with the traffic, the IP address of the client device, the IP address of the server device, the reputation of the server, the names of the client and server devices, etc.
To evaluate traffic between a client device and a server device, the proxy will intercept the communications between the client and server. The intercepted communications are examined by the proxy to determine whether any policy should be applied to the traffic. If it is determined that the traffic should not be blocked, the proxy may cease analyzing the traffic, and allow the client and server to communicate without further delays. Alternatively, if a policy is applied, the proxy may block that traffic or take other actions, as prescribed by the policy.